History of Life Flashcards
define macroevolution
broad pattern of change above a species level
what does macroevol tell us about
emergence of terrestrial vertebrates, mass extinctions, origin of flight in birds
when did earth form
4.6 bya
did early earth have lots of O2
no
process how life originated
- abiotic synthesis of small organic molecules
- joining of smaller mlecules into macromolecules such as proteins and NA
- Packaging of macromolecules into protocells(droplets w/ membrane that separated inside protocell from external env)
- Origin of self-replicating molecules that eventually made inheritcance possible
what is the fossil record biased towards
- hard animals
- widespread distribution
- lived for long
what are the 4 major eons
Hadean, Archaean, Protozeric, Phanerozoic
hadean
beginning of planet to 4 bya
archaean
4 bya to 2.5 bya
proterozoic
2.5 bya-.5 bya
phanerozoic
.5 bya-present
what eras is the phanerozoic divided into
paleozoic, mesozoic, cenozoic
what organisms have dominated life for the majority of time
microbes
when did the first single-celled organism form
3.5 bya
what were earth’s sole inhabitants for 1.5 by
Prokaryotes (bacteria + archaea)
what are the oldest known fossils and when
stromatolites(3.6 bya)
when did O2 begin accumulating
2.7 bya from photosyntehsizing organisms
when was the O2 rev
2.7-2.3 bya
inc O2 levels by 3-4 orders
some were poisoned by this- many prok went extinct
when were the first eukaryotes
1.8 bya via endosymbiosis
when were the first multicellular euk
small algae 1.2 bya
larger and more diverse euk(plants, animals, fungi) not in fossil record until….?
600 mya
multiellularity evolved independelty
cambrian explosion
small window of time(10 million)
btwn protozoic and phanerozoic
appearance of fossils resembling modern animals
first evidence of predator prey interactions in fossil record
soft bodies appeared after
colonizing land
500 mya- fungi, animals, plants on land 420 mya- vascular tissue in plants 365 mya- tetrapods evolved from fish 6-7 mya- origian of human lineage from chimps 200,000 ya- origin of modern humans
what has influenced patterns of diversity
plate tectonics, mass extinctions, adaptive radiation
effects of continental drift on living organism
alters habits in which organisms live, climate on continent could change based on latitude, separation of land masses leads to allopatric speciation
fossils and continental drift
distribution of fossils and living groups relfect historic mbmt of continents
before 135 mya, fossils shared siilarity in parts of south American and africa…..were formerly attached
mass extinctions
vast majority of species ever lived on spanet now extinct(99.9%)
caused by change to a species env
result of disruptive, global, env change
5 majors ones, each with > 50% marine life going extinct
Permean and cretaceous ME
Permian- biggest extinction, 251 mya, btwn paleozoic and mesozoic, volcanism, extinction of 96% oF MArine animals
Cretaceous- not as severe, 65 mya, between mesozoic and cenozoic, 50% of marine species went extinct and dinos went extinct, percentage of marine organisms that were predators increased
define adaptive radiation
rapid speciation rate for 1 lineage from a common ancestor
adaptive radiation
shape distribution of species diversity of organisms
lineages w. novel and advantageous features can be lost during mass extinctions
ME can pave way for AR
usually follows: ME, evol of novel characteristics, and colonization of new regions
global AR
mammals had one after dino extinction
other radiations: photosynthetic prok, large predators in cambrian, land plants, flying insects, waking tetrapods
regional AR
occupy particular regions, not worldwide
organisms colonize new env w/ little comp
ex. hawaiian islands drosophila
macroevolution allow for what?
study of traits
traits and novel traits evolve by tinkering
most novel traits/structures evolve in many stages from previously existing structures
NS an only improve a structure in context of current utility
evolutionary novelties
complex eyes have evolved from simple photosensitive cells independently many times
modern day mollusks show eye structure from patch of pigmented cells to complex lens
evolutionary trends
extracting a single evol progression from fossil record can be misleading
apparent trends should be examined ina broader context
does not imply an intrinsic arive toward a specific ptype
what are the key events in life’s history
origins of unicellular and multicellular organisms and colonization of land
diversity patterns of diff groups of organism reflect differences in ?
speciation
is evol goal oriented?
NO! but selection is
